Boom and jib assembly



Nov. 6, 1962 s. POLLACK 3,06

BOOM AND JIB ASSEMBLY Filed May 11, 1962 2 Sheets-Sheet 1 lNVENTOR s'liyPoZZac/n ATTORNEY Nov. 6, 1962 s. POLLACK 3,062,384

BOOM AND JIB ASSEMBLY Filed May 11, 1962 2 Sheets-Sheet 2 INVENTOR MEmu/4W ATTORNEY United States Patent 6 3,062,384 BOOM AND JIB ASSEMBLYSelig Pollack, Bronx, N.Y., assignor to Seljo Development Crp., Bronx,N.Y., a corporation of New York Filed May 11, 1962, Ser. No. 194,140 6Claims. (Cl. 212144) This invention relates to a jib construction forbooms, derricks, cranes or like manipulating devices. More particularly,this invention relates to an improved boom device of the general typeshOWn in United States Patent No. 3,034,661 of May 15, 1962, whichpatent is based on application Serial No. 58,668, filed September 27,1960, by Joseph Pollack and myself. This application is acontinuation-in-part of the aforesaid joint application.

The aforesaid application is directed to a device having a main,vertically pivotal boom, and a vertically pivotal jib carried adjacent aterminal end of the boom. The angular orientation of the jib withrespect to the horizontal in the aforesaid device is maintainedautomatically constant throughout all adjusted positions of the boom,such automatic orientation of the jib being effected by guying meanswhich articulate the jib with respect to the boom when the latter isarticulated with respect to a base, chassis or other boom support.

The present invention accordingly relates to novel means which whenused, particularly in conjunction with a jib device in accordance withthe above noted patent, enhance the desirable features of such device.

Still more particularly, this invention relates to an improved boomdevice having an adjustable jib characterized by the inclusion of aprestressing apparatus which renders the device safer, more accurate inoperation and easier to use.

Accordingly, it is an object of the invention to provide in combinationwith a boom having an adjustable jib, a prestressing device which urgesthe free or terminal end of the jib downwardly to prevent possibledamage due to shock loading, reduced deflection of the outer end of thejib upon loading, and prevents the possibility of reverse orcounter-rotative movement of the jib with respect to the boom.

A further object of the invention is to provide automatic prestressingapparatus for use with an automatically adjusted jib, such as isillustrated and described in the aforesaid patent, wherein the jib willbe prestressed to a selected level throughout all adjusted positions ofthe boom and jib.

A further object of the invention is to provide a novel boom and jibassembly which includes jib prestressing means which are operative forthe purposes aforesaid and yet do not reduce or detract from the loadcarrying capacity of the jib.

To attain these objects and such further objects as may appear herein orbe hereinafter pointed out, reference is made to the accompanyingdrawings, forming a part hereof, in which FIGURE 1 is a side elevationalview schematically illustrating a device in accordance with theinvention in several positions thereof;

FIGURE 2 is a magnified rear elevation taken in the direction of thearrows 2-2 of FIGURE 1.

Making reference to the drawings, indicates a Caterpiller tractor treadassembly, to which assembly a cab chassis or base assembly 11 has beenmounted for relative movement in a horizontal plane. A main boom 12,having at the lower end thereof a horizontally disposed massive trunnion13 is pivotally mounted to chassis 11 by means of spaced bearing members14 (one being shown) which are fixed to the chassis. The boom 12adjacent its upper terminal end 15 pivotally carries jib member 16 whichis supported on horizontally disposed trunnion assembly 17 made fast tothe upper end of the boom. The boom is thus pivotal in a vertical planeabout a first horizontal axis provided by trunnion 13, and the jib is inturn pivotal vertically with respect to the boom about a secondhorizontal axis provided by trunnion 17.

In Patent 3,034,661 there is illustrated and described a novel guyingarrangement for maintaining the jib 16 automatically in a fixed angularrelation with respect to the horizontal, notwithstanding angulararticulation of the boom 12 about the first axis. Such guyingarrangement will be herein described only to the extent necessary for anunderstanding of the illustrated embodiment of the invention.

A first massive quadrant 20 is fixed to the chassis 111, with thegenerally circular peripheral portion 21 thereof concentrically disposedwith respect to the axis of trunnion 13. A second massive quadrant 22congruent with quadrant 20 is formed on the end 23 of jib 16 and thecircular peripheral portion 25 thereof being concentricmly disposed withrespect to the axis of trunnion assembly 17.

As best seen in FIGURE 2, the quadrants 20, 22 are provided with spacedtrack or guide portions 26, 28, respectively, for receipt of theflexible guy members which control the jib 16. Optionally butpreferably, a first pair 30, 31) of equal lengthened flexible guys,formed of heavy cable, chain or the like, are secured at their upperends 32, 32 to opposed ends 33, 34 of a cross beam 35. The lower ends39a of the guy members are fixed at the lowermost portion of quadrant20. A pair of spaced sheaves 36, 37 are fixed to the upper face of beam35. An upper guy member 40 of similar nature to guy members 30, 30 isreaved through the sheaves, the upper ends 40a, 46a of said guy memberbeing fixed to the uppermost portion of the upper quadrant 22. Aturnbuckle 41 is optionally but preferably interposed in guy 40 topermit variation of the tension in such guy.

The net result of such guying arrangement, as fully set forth in theaforesaid patent, is to cause the jib 16 to articulate about trunnion 17as the boom 12 is articulated about trunnion 13 by reason of the windingand unwinding of guys 30 and 40 about quadrants 22 and Zil,respectively. The Winding and unwinding action aforesaid causes the jibto be maintained in fixed angular relation to the horizontal throughoutall reach and retractive movements of boom 12. The incorporation in theconstruction aforesaid of the beam 35 is particularly advantageous inthat it permits the use of quadrants which are of different widths, i.e.the lower quadrant 26 may be of a greater lateral dimension than theupper quadrant 22, in conformity with the relatively narrow jib width.Similarly, the provision of a unitary upper guy which passes undersheaves 36, 37 assures that the two segments of the guy 40 will be ofequal length at all times. The turnbuckle 41 permits length adjustmentof guy member 41 for accurate angular orientation of the jib.

The prestressing of the jib is effected by a quadrant assembly similarto the jib control assembly above described. The prestressing assemblyincludes a lower quadrant mounted on chassis plate 14 and having agenerally circular peripheral surface which is concentrically disposedwith respect to and positioned beneath lower trunnion 13. An upperquadrant is fixed to jib 16 beneath trunnion 17, said upper quadrantbeing congruent with respect to the quadrant 56 and including a circularperipheral portion 56 which is concentrically disposed with respect tothe upper trunnion assembly 17. The surfaces 51 and 56 of quadrants 5t55 are spaced from trunnions 13 and 17, respectively, in a manner to "3dispose the axes of said trunnions at the radii of the respectivearcuate surfaces 51 and 56.

The quadrants 5t} and are guyed to each other by a heavy flexible guyassembly 69. While the assembly may comprise a single guy wrapped overguadrants 50 and 55, tangentially to engage surfaces 51 and 56 thereofin all articulated positions of the boom, the assembly 651 is preferablyformed of upper and lower paired guy segments separated by a beam, asemployed for the main quadrants 2t) and 22. In such preferred guyingassembly, only the right hand side of which may be seen in FIG- URE 1, apair of lower guy members 61 are fixed at their lower ends 62 beneaththe arcuate section 51 of said lower quadrant. The upper ends 63 of saidguy members are fixed to beam 65 in laterally spaced-apart relation. Apair of sheaves 66 are fixed in laterally spaced relation to the uppersurface of beam 65, a single strand 67 of heavy flexible guying beingpassed beneath both the sheaves 66. The uppermost ends 68 of the strand67 are fixed at the uppermost edges of the peripheral surface 56 ofquadrant 55. A turnbuckle 69 is interposed in the strand and by theadjustment of such turnbuckle, the tension in the entire prestressingguy assembly 60 may be varied.

It will be seen from the above described guying assembly that as boom 12is articulated, the jib 16 is likewise articulated and the guy 60 willbe wrapped on one of the quadrants at the same rate as the same isunwrapped from the other quadrant and, thus, the distance or length ofguy 60 disposed between the points of tangential engagement of the guyand the quadrants 50, 55 will remain substantially the same throughoutall movements of the boom.

In FIGURE 1, lift hooks 70 and 71 represent load carrying elementsreaved through support elements (not i shown) made fast to the jib 16.

When a load is applied to jib 16, for instance by application of theload to hooks 70 or 71, the applied force tends to rotate the jibclockwise, as shown in dot and dash lines, FIGURE 1, about trunnion 17.In the absence of a prestressing force, the unloaded jib will, asexaggeratedly shown in dot and dash lines, FIGURE 1 (intermediateposition), occupy a position in which the jib is counterclockwiselyrotated about trunnion 17 as compared to the position such jib willoccupy when loaded. The counterclockwise rotation is due in part to theforce generated by the weight of the jib control guy assembly. Suchcounter-rotative force becomes increasingly great as the boom islowered, i.e. as the jib control guy approaches a theoretical catenaryposition as shown in the lowermost dot and dash view of FIGURE 1.

Where, as in the device of Patent No. 3,034,661, there is a dendency tocounter-rotative movement of the jib, the application of a load to suchjib will cause an immediate and considerable clockwise rotation of thejib, which rotation will be abruptly arrested as the jib control guysare fully extended. The shock of such abruptly arrested forces,repetitively encountered, will result in an undue amount of wear, andalso possible fracture of certain of the force absorbing elements of thedevice, rendering frequent repairs probable and leaving a possibility ofdisastrous consequences.

A further undesirable effect encountered in the use of an un-prestressedjib is that the relatively large jib encounters deflection when such ajib is first loaded, rendering uncertain the ultimate, loaded anglewhich will be assumed by the jib. To be able accurately to determine theultimate angle which will be assumed by the jib is of particularimportance where a continued horizontal disposition of the jib issought, as where the jib is provided with tracks and with alongitudinally shiftable trolley which may be shifted along such tracks.Such an arrangement is illustrated in the above noted patent.

The prestressing quadrant and guying assembly above described eliminatesall the above noted disadvantages by stressing the jib substantially tothe position it will ultimately occupy when loaded. Thus, the anglewhich the jib will ultimately occupy will be nearly exactly ascertainedand the addition of the load will not vary the same. Also, since thereis no movement of any substantial magnitude, the addition of a load tothe jib will not induce any sudden shock to the device, thus eliminatingthe disadvantages previously noted as existing in un-prestressed jibs.Also, the prestressing device will prevent the jib from fallingbackward, an action which may occur in unloaded and un-prestressed jibs,particularly where the boom is raised and abruptly stopped.

It is of particular importance to note that the prestressing deviceherein disclosed does not detract from the load carrying capacity of thejib. This important feature is due to the fact that the slightadditional deflection induced in the jib by the addition of a loadrelaxes the pressure exerted by the guying system of the prestressingassembly, and thus the prestressing forces are effective only when theyare required, i.e. when the jib is unloaded. This should be compared toprestressing through the use, for instance, of a weight. If acounterweight were employed for the purpose of prestressing the jib,this weight would also exert a deflecting force on the jib and boom whena load was supported on the jib, thereby detracting from the effectiveload carrying capacity of the device.

A further desirable feature of the prestressing device lies in the factthat the prestressing force exerted is automatically varied inaccordance with the position of the boom. As pointed out above, theupsetting force exerted by the jib control guy assembly 40 increasesprogressively as the boom is lowered, i.e. as the guy assemblyapproaches a horizontal or catenary conformation. It will be readilyrecognized that the prestressing guy assembly similarly exerts a greaterforce as the boom is progressively lowered and as it approaches thecatenary, thus offsetting the increasing upsetting effects of thecontrol guy assembly. Preferably, the two guy assemblies are disposed inparallelism.

From the above it will be seen that there is provided a novel craneassembly having means for applying a prestressing force to the jib,which force will be applied automatically in all adjusted positions ofthe jib and which force will be relieved when a pay load is placed onthe jib.

The prestressing feature is particularly useful when employed inconjunction with a self-leveling (or self-adjusting, if horizontaldisposition is not required) jib assembly as shown in Patent No.3,034,661.

By the use of the turnbuckles in the prestressing guy or tie assembly,shock loading resulting from counterdeflection of the jib and/orslackness in the jib control guy assembly may be eliminated, or at leastgreatly reduced. Similarly, the jib may be angularly oriented to adesired position with the knowledge that the addition of a load to thejib will not materially vary the position of the jib.

While the invention is described as utilized in conjunction with acaterpillar tractor base, it will be readily recognized that the samewill be applicable in a wide variety of applications and, hence, theinvention should be broadly interpreted within the scope of the appendedclaims.

Having thus described the invention and illustrated its use, what isclaimed as new and is desired to be secured by Letters Patent is:

1. A crane rigging device comprising a supporting base chassis, a mainboom pivotally supported on said chassis on a first horizontal axis, tobe pivotable in a vertical plane, a beam jib having a free end and aninner end pivotally mounted about a second horizontal axis on bearingmeans disposed adjacent the upper terminal end of said boom, a firstpair of congruent quadrant means fixed, respectively, to said chassisand said jib, first flexible guy means engaging said first pair ofquadrant means tangentially in all vertically pivoted positions of saidboom with respect to said chassis, a second pair of congruent quadrantmeans, one of said second pair being fixed with respect to said chassisand the other of said pair being fixed with respect to said jib, theperipheries of the quadrants of said second pair being downwardlydirected and concentrically disposed with respect to said first andsecond horizontal axes, respectively, and disposed in opposition to theperipheries of said first pair, second flexible guy means tangentiallycontacting the peripheries of said second pair of quadrants and meansfor stressing said second guy means.

2. A crane rigging device comprising a supporting base chassis, a mainboom pivotally supported on said chassis on a first horizontal axis, tobe pivotable in a vertical plane, a beam jib having a free end and aninner end mounted pivotally about a second horizontal axis on hearingmeans disposed adjacent the upper terminal end of said boom, loadsupport means operatively connecting said jib and said chassis formaintaining a fixed angular relationship between said jib and thehorizontal throughout all vertically pivoted positions of said boom withrespect to said chassis and means applying a downward stress to saidfree end of said jib in the unloaded condition of said jib throughoutall vertically pivoted positions of said boom with respect to saidchassis comprising first and second members including quadrant portionshaving congruent peripheries, said members being mounted, respectively,on said chassis and said jib, with said peripheral portionsconcentrically located with respect to said first and second axes,respectively, and flexible guy means tangentially engaging saidperipheries throughout all vertically pivoted positions of said boomwith respect to said chassis.

3. In a crane rigging device having a main boom and a supporting basechassis upon which said boom is pivoted for retraction and reach, a beamjib pivoted at one end on a horizontal axis adjacent the upper terminalend of said boom and having a free end spaced from said boom and jibsupport and control means including guying means for articulating saidjib to maintain the jib automatically in fixed angular relation to thehorizontal in all angular relations of the boom and chassis, thecombination of prestressing means for said jib comprising first andsecond congruent quadrant members mounted, respectively, on said jib andsaid chassis, a flexible guy member tangentially engaging theperipheries of said first and second quadrant members and having itsupper and lower end portions operably connected, respectively, with saidjib and chassis, said guy member being tensioned to urge said free endof said jib downwardly.

4. A crane device comprising a base chassis, a main boom mounted on saidchassis for pivotal movement about a first horizontal axis, a beam jibhaving a free end and an end mounted adjacent the upper terminal end ofsaid boom for pivotal movement about a second horizontal axis, jibsupport and control means for articulating said jib about said secondaxis responsive to vertical pivotal movement of said main boom withrespect to said chassis to maintain said jib automatically in fixedangular relation to the horizontal, and means stressing said free end ofsaid jib downwardly comprising first and second congruent quadrantmembers mounted, respectively, on said jib and chassis, said quadrantmembers being disposed concentrically with respect to said first andsecond horizontal axes, respectively, and flexible guy means undertension and having its opposite ends operably connected to said jib andchassis and tangentially engaging an undersurface of both said quadrantsin all adjusted positions of said boom about said first axis.

5. A crane device comprising a main boom mounted on a support to bepivotal about a first horizontal axis, a jib having a free end and anend mounted to said main boom to be pivotal about a second horizontalaxis, means for automatically articulating said jib with respect to saidboom as said boom pivots about said first axis to maintain said jib at afixed angle with respect to the horizontal, and means for prestressingsaid free end of said jib downwardly in all articulated positions ofsaid jib with respect to said boom, comprising first and second take-upmeans having downwardly directed, generally circular portions operablyconnected, respectively, to said support and said jib, flexible guymeans connected between said take-up means and tangentially engagingsaid circular portions, the distance between the points of said guymeans engaged with said circular portions being substantially constantin all positions of said jib and boom.

6. A device in accordance with claim 5 and including means for varyingthe tension in said guy.

No references cited,

